1. Field
The disclosed technology relates to an exposure apparatus for thin film deposition, a method of controlling the same, and an alignment method for exposure, and more particularly, to the use of a feedback loop to more precisely control the position of components of the apparatus undergoing movement and thereby accurately calibrate the patterning of a thin film.
2. Description of the Related Technology
In a general thin film exposure apparatus, light emitted from a light source is irradiated onto a mask, is passed through an opening patterned in the mask, and then is incident on a substrate. As such, light is irradiated onto a preset region of the substrate in a corresponding shape of the opening patterned in the mask.
In the above-described exposure process, in order to accurately expose the preset region of the substrate in a corresponding shape of the opening patterned in the mask, alignment of the mask or the substrate is a significant concern.
For example, a typical process is a laser-induced thermal imaging (LITI) process in which a laser beam emitted from a light source is passed through and is shaped by using a mask. The shaped laser beam reaches a donor film so as to transfer a certain amount of the organic or inorganic material as a thin film layer onto a substrate. Before the LITI process is initiated, the laser beam should be accurately aligned to be incident at a preset position (e.g., a certain sub-pixel region) of a substrate on which, for example, a thin film transistor (TFT) is formed This is because a defective electronic product will be produced if the laser beam has an unintended shape or is irradiated onto an unintended region of the substrate.
Accordingly, since alignment of a mask and the position of a region for thin film deposition, a TFT, for example, related to the shape of a laser beam are set in advance, alignment of a substrate on which a region onto which the laser beam is irradiated is critical.
However, in conventional thin film exposure systems, when exposure is repeatedly performed, the accuracy of exposure of the exposure apparatus is reduced due to the influence of aging or the influence of heat, for example. That is, since the driving unit ages due to variations in ambient environmental conditions over time and variations in position of a light source (typically a laser beam) due to heat generated from the exposure process, position errors in exposure patterns are induced.